title: Complement regulatory protein Crry/p65 costimulation expands natural treg cells with enhanced suppressive properties in proteoglycan-induced arthritis.
abstract: OBJECTIVE
  To investigate the costimulatory role of Crry/p65 (Crry), a membrane complement regulatory protein, on the expansion and function of natural Treg cells and their ability to ameliorate proteoglycan-induced arthritis (PGIA), an animal model of inflammatory arthritis in which the role of natural Treg cells is not well established.
  
  
  METHODS
  CD4+CD25+ natural Treg cells from BALB/c mice were activated in vitro and costimulated by Crry. The expanded cells were phenotypically characterized, and their suppressive effect on T cell proliferation was assayed in vitro. The potential prophylactic and therapeutic effects of this population versus those of natural Treg cells in PGIA were studied. The clinical score, histology, the antigen-specific isotype antibody pattern, in vitro T cell responses, and the presence of Treg cells in the paws were studied.
  
  
  RESULTS
  Crry costimulation enhanced the in vitro expansion of natural Treg cells while maintaining their phenotypic and suppressive properties. Crry-expanded Treg cells had stronger suppressive properties in vivo and a longer ameliorating effect in the PGIA model than did natural Treg cells. Crry-expanded Treg cells suppressed T cell- and B cell-dependent responses in PGIA, changing the pathogenic antibody isotype pattern and decreasing antigen-dependent secretion of cytokines, including interferon-γ, interleukin-12 (IL-12), and IL-17. Increased FoxP3 expression was detected in the paws of mice transferred with Crry-expanded Treg cells.
  
  
  CONCLUSIONS
  Crry-mediated costimulation facilitates in vitro expansion of natural Treg cells while maintaining their suppressive properties in vitro and in vivo in the PGIA model. These results highlight the potential of the complement regulatory protein Crry to costimulate and expand natural Treg cells capable of suppressing disease in an animal model of chronic inflammatory arthritis.
authors.affiliation: Unidad de Inmunología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Gloria
authors.initials: G
authors.lastname: Ojeda
authors.forename: Eliana
authors.initials: E
authors.lastname: Pini
authors.forename: César
authors.initials: C
authors.lastname: Eguiluz
authors.forename: María
authors.initials: M
authors.lastname: Montes-Casado
authors.forename: Femke
authors.initials: F
authors.lastname: Broere
authors.forename: Willem
authors.initials: W
authors.lastname: van Eden
authors.forename: Jose M
authors.initials: JM
authors.lastname: Rojo
authors.forename: Pilar
authors.initials: P
authors.lastname: Portolés
mesh_terms: D000818:Animals; D001168:Arthritis / Q000139:chemically induced / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D005260:Female; D051858:Forkhead Transcription Factors / Q000096:biosynthesis; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011509:Proteoglycans / Q000009:adverse effects; D011951:Receptors, Complement / Q000276:immunology*; D017463:Receptors, Complement 3b; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: C081470:Cr1l protein, mouse; D016207:Cytokines; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit; D011509:Proteoglycans; D011951:Receptors, Complement; D017463:Receptors, Complement 3b